A visit to a doctor's office, a clinic or a hospital may necessitate vascular access that is, the insertion of a needle or catheter into a patient's vein or artery. These procedures may be required for the following reasons: to administer fluids, drugs or solutions, to obtain and monitor vital signs, to place long-term access devices, and to perform simple venipunctures. Vascular access ranks as the most commonly performed invasive, medical procedure in the U.S—over 1.4 billion procedures annually—as well as the top patient complaint among clinical procedures. The overwhelming majority of vascular access procedures is performed without the aid of any visualization device and relies on what is observed through the patient's skin and by the clinician's ability to feel the vessel. Medical literature reports the following statistics: 28% first attempt IV failure rate in normal adults, 44% first attempt IV failure in pediatrics, 43% of pediatric IVs require three or more insertion attempts, 23% to 28% incidence of extravasations/infiltration, 12% outright failure rate in cancer patients, 25% of hospital in-patients beyond three days encounter difficult access.
It is known in the art to use an apparatus to enhance the visual appearance of the veins in a patient to facilitate insertion of needles into the veins. An example of such a system is described in U.S. Pat. Nos. 5,969,754 and 6,556,858 incorporated herein by reference as well as a publication entitled “The Clinical Evaluation of Vein Contrast Enhancement”. Luminetx is currently marketing such a device under the name “Veinviewer Imaging System” and information related thereto is available on its website, which is incorporated herein by reference.
The Luminetx Vein Contrast Enhancer (hereinafter referred to as LVCE) utilizes an infrared light source for flooding the region to be enhanced with infrared light generated by an array of LEDs. A CCD imager is then used to capture an image of the infrared light reflected off the patient. The resulting captured image is then projected by a visible light projector onto the patient in a position closely aligned with the image capture system. Given that the CCD imager and the image projector are both two dimensional, and do not occupy the same point in space, it is relatively difficult to design and build a system that closely aligns the captured image and the projected image.
A further characteristic of the LVCE is that both the imaging CCD and the projector have fixed focal lengths. Accordingly, the patient must be at a relatively fixed distance relative to the LVCE. This necessitates that the LVCE be positioned at a fixed distance from the region of the patient to be enhanced.
The combination of the size of the LVCE and the fixed focal arrangement precludes using the LVCE as small portable units that are hand held.
Other patents such as U.S. Pat. No. 6,230,046, issued to Crane et al. assigned to The United States of America as represented by the Secretary of the Air Force, implement a light source for illuminating or transilluminating the corresponding portion of the body with light of selected wavelengths and a low-level light detector such as an image intensifier tube (including night vision goggles), a photomultiplier tube, photodiode or charge coupled device, for generating an image of the illuminated body portion, and optical filter(s) of selected spectral transmittance which can be located at the light source(s), detector, or both.
All citied references are incorporated herein by reference in their entireties. Citation of any reference is not an admission regarding any determination as to its availability as prior art to the claimed invention.